6521. 题目: Economic losses of carbon emissions from circum-Arctic permafrost regions under RCP-SSP scenarios
期刊: Science of The Total Environment
作者: Yating Chen, Aobo Liu, Zhihua Zhang, Chris Hope, M. James C. Crabbe
摘要: Under rapid Arctic warming, the vast amount of labile organic carbon stored in Arctic permafrost soils poses a potentially huge threat. Thawing permafrost will release hundreds of billion tons of soil carbon into the atmosphere in the form of CO2 and CH4 that would further intensify global warming and bring more challenges to human society. In this study, we use the PInc-PanTher model to estimate carbon emissions from thawing permafrost in the circum-Arctic during 2010–2100 followed by the PAGE09 integrated assessment model to evaluate the net economic losses caused by these permafrost carbon emissions. Our results show that in terms of net present value (NPV), the release of CO2 and CH4 from circum-Arctic permafrost will generate estimated net economic losses of US$2.5 trillion (5–95% range: 0.3–11.2 US$ trillion) under the RCP4.5-SPP1 scenario and US$12.7 trillion (5–95% range: 1.6–41.8 US$ trillion) under the RCP8.5-SPP3 scenario between 2010 and 2100, which contribute ~4.9% and ~6.4% respectively of net economic losses of global carbon emissions.
6522. 题目: Substituted Aromatic-Facilitated Dissemination of Mobile Antibiotic Resistance Genes via an Antihydrolysis Mechanism Across an Extracellular Polymeric Substance Permeable Barrier
期刊: Environmental Science & Technology
作者: Weijun Shou, Fuxing Kang, Shuhan Huang, Chunyao Yan, Jiaxin Zhou, Yijin Wang
摘要: Mobile antibiotic resistance genes (ARGs) in environmental systems may pose a threat to public health. The coexisting substituted aromatic pollutants may help the ARGs cross the extracellular polymeric substance (EPS) permeable barrier into the interior of cells, facilitating ARG dissemination, but the mechanism is still unknown. Here, we demonstrated that a specific antihydrolysis mechanism of mobile plasmid in the extracellular matrix makes a greater contribution to this facilitated dissemination. Specifically, fluorescence microtitration with a Tb3+-labeled pUC19 plasmid was used to study the formation of substituted aromatic–plasmid complexes associated with ARG dissemination. Manipulations of the endA gene and an EPS confirmed that these forming complexes antagonize the EPS-mediated hydrolysis of the plasmid. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and computational chemistry demonstrated that substituents alter the polarity of aromatic molecules, making the carbon at the 6-position of 1,3-dichlorobenzene as well as the labile protons (−NH2/–OH) of m-phenylenediamine, aniline, and 2-naphthol interact with the deprotonated hydroxy group of the phosphate (P–O···H–C/N/O), mainly via hydrogen bonds. Linear correlations among ARG disseminations, association constants, and bonding energies highlight the quantitative dependency of ARG proliferation on a combination of functionalities templated by d-ribose–phosphate.
6523. 题目: Real-Time Monitoring of Ligand Exchange Kinetics on Gold Nanoparticle Surfaces Enabled by Hot Spot-Normalized Surface-Enhanced Raman Scattering
期刊: Environmental Science & Technology
作者: Haoran Wei, Weinan Leng, Junyeob Song, Chang Liu, Marjorie R. Willner, Qishen Huang, Wei Zhou, Peter J. Vikesland
摘要: Nanoparticle surface coatings dictate their fate, transport, and bioavailability. We used a gold nanoparticle–bacterial cellulose substrate and “hot spot”-normalized surface-enhanced Raman scattering (HSNSERS) to achieve in situ and real-time monitoring of ligand exchange reactions on the gold surface. This approach enables semiquantitative determination of citrate surface coverage. Following exposure of the citrate-coated nanoparticles to a suite of guest ligands (thiolates, amines, carboxylates, inorganic ions, and proteins), the guest ligand signal exhibited first-order growth kinetics, while the desorption mediated decay of the citrate signal followed a first-order model. Guest ligand functional group chemistry dictated the kinetics of citrate desorption, while the guest ligand concentration played only a minor role. Thiolates and BSA were more efficient at ligand exchange than amine-containing chemicals, carboxylate-containing chemicals, and inorganic salts due to their higher binding energies with the AuNP surface. Amine-containing molecules overcoated rather than displaced the citrate layer via electrostatic interaction. Citrate exhibited low resistance to replacement at high surface coverages, but higher resistance at lower coverage, thus suggesting a transformation of the citrate-binding mode during desorption. High resistance to replacement in streamwater suggests that the role of surface-adsorbed citrate in nanomaterial fate and transport must be better understood.
6524. 题目: Direct Evidence for Temporal Molecular Fractionation of Dissolved Organic Matter at the Iron Oxyhydroxide Interface
期刊: Environmental Science & Technology
作者: Elizabeth K. Coward, Tsutomu Ohno, Donald L. Sparks
摘要: While the importance of organic matter adsorption onto reactive iron-bearing mineral surfaces to carbon stabilization in soils and sediments has been well-established, fundamental understanding of how compounds assemble at the mineral interface remains elusive. Organic matter is thought to layer sequentially onto the mineral surface, forming molecular architecture stratified by bond strength and compound polarity. However, prominent complexation models lack experimental backing, despite the role of such architecture in fractionated, compound-dependent persistence of organic matter and modulating future perturbations in mineral stabilization capacity. Here, we use kinetic assays and ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry under high temporal frequency to directly detect the molecular partitioning of organic matter onto an iron oxyhydroxide during adsorption. We observed three sequential intervals of discrete molecular composition throughout the adsorption reaction, in which rapid primary adsorption of aromatic compounds was followed by secondary lignin-like and tertiary aliphatic compounds. These findings, paired with observed differential fractionation along formulas nitrogen and oxygen content and decreasing selective sorption with reaction time, support “zonal” assembly models. This work presents direct detection of sequential molecular assembly of organic matter at the mineral interface, an important yet abstruse regulator of carbon stabilization and composition across temporal and spatial scales.
6525. 题目: Is vermicompost the possible in situ sorbent? Immobilization of Pb, Cd and Cr in sediment with sludge derived vermicompost, a column study
期刊: Journal of Hazardous Materials
作者: Yaxin Zhang, Ye Tian, Duofei Hu, Jinshi Fan, Maocai Shen, Guangming Zeng
摘要: The goal of this study was to investigate the immobilization effect of vermicomposted sewage sludge for Pb, Cd and Cr in the sediment under simulated in situ conditions using column test. Positioning 10 % dw of vermicompost at the bottom layer of the column resulted in an average decrease of Pb, Cd and Cr in the leachate of 93, 97 and 75.5 %, with the accumulated adsorbed amount of 11.80, 4.81 and 5.62 mg g-1, respectively. Fluorescence Excitation‒Emission Matrix (EEM) combined with parallel factor analysis (PARAFAC) was adopted to identify the components in DOM (dissolved organic matter) that were efficient for the immobilization of heavy metals. The 4‒component PARAFAC model established showed that DOM was dominated by a protein‒like material (component C1), and three humic‒like materials (component C2, C3 and C4). The humic substances formed the organo‒metal complexes with Pb, Cr and Cd, hence, the metal ions were sequestered by the sorbent. Also, as calculated by the bivariate coefficients, the C2/C1 ratios can be liable parameters for assessing the retaining capability of vermicompost for heavy metals. Generally, vermicompost can be used as a promising in situ sorbent for the remediation of heavy metal polluted sediments.
6526. 题目: Centennial-scale climate variability during the past 2000 years derived from lacustrine sediment on the western Tibetan Plateau
期刊: Quaternary International
作者: Xiumei Li, Mingda Wang, Juzhi Hou
摘要: The Tibetan Plateau (TP) climate change has been suggested to be modulated by the Asian monsoon and the westerly jet at seasonal, decadal, millennial and glacial-interglacial scales, which demonstrated evident regional variation. However, due to the lack of high resolution climate records, how the climate changed and how the regional environment was influenced by the monsoon and the westerlies on the western Tibetan Plateau (WTP) during the late Holocene remains unclear. Here we present multiple palaeo-climatic proxy records in sediment core from Xiada Co in the WTP for the past 2000 years, based on the relative distribution of branched glycerol dialkyl glycerol tetraethers (brGDGTs), n-alkanoic acid average chain length (ACL) and percent aquatic inputs (Paq), XRF, total organic carbon (TOC) and inorganic carbon (TIC) concentration. The centennial-scale variation of the climate records captures well-known climatic events over the past 2000 years, for example, the cool-dry ‘Little Ice Age’ (LIA) and the warm-wet ‘Medieval Warm Period’ (MWP). Besides, the multi-proxy indicated a severe dry event during 350-250 cal yr BP and a cool-wet climate during the past 200 years. This study concludes that Xiada Co was mainly influenced by the Indian monsoon during the past 2000 years. In addition, the temperature variability appears to correspond to solar irradiance changes, suggesting a significant solar influence on temperature variability in the WTP. Our results suggest that the abrupt drought near 320 cal yr BP may be the key factor leading to the demise of the Guge Kingdom.
6527. 题目: Characteristics of nitrogen and phosphorus adsorption by Mg-loaded biochar from different feedstocks
期刊: Bioresource Technology
作者: Yan-Hong Jiang, An-Yu Li, Hua Deng, Cheng-Hui Ye, Yu-Qing Wu, Yu-Dan Linmu, Hao-Lin Hang
摘要: Herein, biochars from 6 different feedstocks (taro straw, corn straw, cassava straw, Chinese fir straw, banana straw, and Camellia oleifera shell) were produced using magnesium chloride (MgCl2) as a modifier due to their sorption behavior toward NH4+-N and phosphorus in an aqueous solution.The biochar characteristics were evaluated, including pH, pHPZC, biochar magnesium content, and total pore volume (PVtot). The experimental results in terms of the kinetics and equilibrium isotherms showed that the cassava straw and banana straw biochars exhibited the theoretical maximum saturated adsorption capacities of 24.04 mg·g-1 (NH4+-N) and 31.15 mg·g-1 (TP), respectively. Biochar produced from these feedstocks had higher magnesium contents and greater total pore volumes, reflecting the significant contributions from magnesium and steric effects. FTIR, XRD, and SEM/EDS analyses demonstrated that NH4+-N and TP sorption mechanisms predominantly involved surface electrostatic attraction, Mg2+ precipitates and complexation with surface hydroxyl functional groups.
6528. 题目: Kinetic and microbial response of activated sludge community to acute and chronic exposure to tetracycline
期刊: Journal of Hazardous Materials
作者: Ilke Pala-Ozkok, Emine Ubay-Cokgor, Daniel Jonas, Derin Orhon
摘要: Current study aimed to discover both kinetic and microbial response of activated sludge biomass to continuous exposure to tetracycline, one of the most frequently detected antibiotics in wastewaters. Respirometric analysis and model evaluation of the oxygen utilization rate profiles generated at critical phases of the experimental period showed that, continuous exposure to tetracycline caused complete suppression of substrate storage aside from mild inhibition on the growth kinetics and it exerted a significant binding action with available organic carbon, leading to less oxygen consumption. Additionally, increase in endogenous decay rates by 1.5 fold was associated with maintenance energy dictated by the presence and production of antibiotic resistance genes, as demonstrated by resistance gene profile. High-throughput sequencing results showed that continuously exposure to tetracycline caused a significant shift in the community structure at species level so that tetracycline resistant bacteria like Arthrobacter sp and Diaphorobacter sp dominated the bacterial community.
6529. 题目: Saltwater intrusion and soil carbon loss: Testing effects of salinity and phosphorus loading on microbial functions in experimental freshwater wetlands
作者: Shelby Servais, John S. Kominoski, Sean P. Charles, Evelyn E. Gaiser, Viviana Mazzei, Tiffany G. Troxler, Benjamin J. Wilson
摘要: Wetlands can store significant amounts of carbon (C), but climate and land-use change increasingly threaten wetland C storage potential. Carbon stored in soils of freshwater coastal wetlands is vulnerable to rapid saltwater intrusion associated with sea-level rise and reduced freshwater flows. In the Florida Everglades, unprecedented saltwater intrusion is simultaneously exposing wetlands soils to elevated salinity and phosphorus (P), in areas where C-rich peat soils are collapsing. To determine how elevated salinity and P interact to influence microbial contributions to C loss, we continuously added P (~0.5 mg P d−1) and salinity (~6.9 g salt d−1) to freshwater Cladium jamaicense (sawgrass) peat monoliths for two years. We measured changes in porewater chemistry, microbial extracellular enzyme activities, respiration rates, microbial biomass, root litter breakdown rates (k), and soil elemental composition after short (57 d), intermediate- (392 d), and long-term (741 d) exposure. After 741 days, both β-1,4-glucosidase activity (P < 0.01) and β-1,4-cellobiosidase activity (P < 0.01) were reduced with added salinity in soils at 7.5–15 cm depth. Soil microbial biomass C decreased by 3.6× at 7.5–15 cm (P < 0.01) but not 0–7.5 cm depth (P > 0.05) with added salinity and was unaffected by added P. Soil respiration rates decreased after 372 d exposure to salinity (P = 0.05) and did not change with P exposure. Root litter k increased by 1.5× with added P and was unaffected by salinity exposure (P > 0.01). Soil %C decreased by approximately 1.3× after 741 days of salinity exposure compared to freshwater controls (P < 0.01). Elevated salinity and P accelerated wetland soil C loss primarily through leaching of DOC and increased root litter k. Our results indicate that freshwater wetland soils are sensitive to short- and long-term exposure to saltwater intrusion. Despite suppression of some soil microbial processes with added salinity, salt and P exposure appear to drive net C losses from coastal wetland soils.
6530. 题目: Organic carbon dynamics in soils of Mid-Atlantic barrier island landscapes
作者: Ann M. Rossi, Martin C. Rabenhorst
摘要: Geomorphic processes associated with coastal wetlands often result in high carbon accumulation rates and relatively large carbon stocks. Barrier islands are an important component of coastal ecosystems and freshwater and brackish wetlands on these islands provide an important habitat for a number of animal and plant species. However, organic carbon dynamics in these landscapes have received relatively little attention. The objective of this study was to document the accumulation of organic carbon and understand the factors influencing soil carbon dynamics on barrier islands. Ten topographic transects were established on different landforms on Assateague Island National Seashore, MD, USA. Soil organic carbon stocks, aboveground carbon inputs, and decomposition rates were compared among landforms (representing differing degrees of landform stability and soil age) and drainage conditions. Soil organic carbon stocks (0–1.0 m) ranged from 0.49 to 18.8 kg C m−2, and increased in magnitude with soil age. Higher carbon stocks in the older soils were partly attributed to the increased time over which carbon had accumulated. Additionally, a shift from herbaceous dominated to forest dominated plant communities led to greater carbon inputs in older soils. Carbon stocks were also greater in the very poorly and poorly drained soils (relative to drier soils) where high levels of carbon inputs (plant biomass) exceed decomposition rates, which were slowed under anaerobic conditions. While rates of carbon accumulation (average 0.021 kg C m−2 yr−1) are somewhat low compared to other more productive systems, barrier island soils have the potential to store large amounts of organic carbon (relative to other soils) as organic-rich surface horizons are buried during overwash events.
6531. 题目: UV-activated persulfate oxidation of 17β-estradiol: Implications for discharge water remediation
期刊: Journal of Environmental Chemical Engineering
作者: A. Angkaew, C. Sakulthaew, T. Satapanajaru, C. Chokejaroenrat
摘要: The female sexual hormone, 17β-estradiol (E2), was chosen as a model emerging contaminant to study its degradation kinetics using UV-activated persulfate (UV/PS). Our objective was to quantify the effectiveness of UV/PS coupled with slow-release technology to degrade E2 in real wastewater using a systematic design flow-through system. This was accomplished by quantifying the effects on E2 degradation rates of the initial PS or E2 concentration, initial pH, constituent ions, turbidity, humic acids, and real wastewater. The results showed that the E2 degradation rates increased with increasing PS concentration. The presence of other constituent ions (NO3–, Cl–, HCO3–) resulted in varying degradation rates due to the formation of active and less reactive radicals. Humic acid had higher significant impact on the rates than did turbidity. In addition, the observed degradation rates (0.140 min-1) in Deionized water were much higher than those observed in real wastewater matrix (0.001 min-1). Biodegradable soywax was the best binding agent that provided sustained delivery of PS thus resulting in better E2 removal than with other waxes. But treating E2 with PS soywax in a wastewater matrix, our flow-through system was able to maintain the E2 concentration below 50% in the contact tank (~150 min) and able to continually remove E2 up to 65% (~240 min) in the effluent reservoir. The overall results supported the use of UV-activated slow-release PS to treat discharge water in animal farming.
6532. 题目: Diagenetic mobilization of Ti and formation of brookite/anatase in early Cambrian black shales, South China
期刊: Chemical Geology
作者: Ze-Rui Ray Liu, Mei-Fu Zhou, Anthony E. Williams-Jones, Wei Wang, Jian-Feng Gao
摘要: Titanium (Ti) is typically hosted in detrital minerals in marine sediments and has long been considered to be immobile during diagenesis. In this study, the authigenic titania minerals, brookite and anatase, are observed in early Cambrian carbonaceous shales from the Meishucun and Zhajin sections of South China, respectively. Black shales in the Meishucun section have total organic carbon (TOC) contents from 1.6 to 3.9 wt% and HI (hydrogen index) values from 3.8 to 20 mg HC/g TOC, whereas black shales in the Zhajin section have much higher TOC (7.1–15.6 wt%) but lower HI (<2.0 mg HC/g TOC) and contain abundant bitumen (~3 vol%). Brookite in black shales from the Meishucun section crystallized invariably along cleavages of detrital biotite. This intimate association suggests that the Ti required to form titania minerals was derived from detrital biotite and that Ti was mobilized only on a nano- to micro-meter scale. In contrast, anatase aggregates in black shales from the Zhajin section are intergrown with bitumen. It is proposed that Ti in these shales was mobilized in low pH organic-rich fluids and, subsequently, preferentially precipitated as anatase with increasing pH. The mobilization of inert Ti in black shales is indicative of a possible diagenetic or post-diagenetic elemental redistribution in carbonaceous rocks. Our study further demonstrates that proxies based on geochemical component of black shales can be employed to estimate redox state of ancient oceans, but must be applied with caution.
6533. 题目: Soil Organic Carbon and Isotope Composition Response to Topography and Erosion in Iowa
期刊: Journal of Geophysical Research: Biogeosciences
作者: Xia Li, Gregory W. McCarty, Douglas L. Karlen, Cynthia A. Cambardella, William Effland
摘要: Soil redistribution (erosion and deposition) can greatly affect the fate of soil organic carbon (SOC) in agroecosystems. Landscape topography is one of the key factors controlling erosion processes and creating spatial variability in SOC. We combined carbon (C) isoscape (isotopic landscape) analysis, historic orthophoto interpretation, cesium (137Cs) inventory measurement, and digital terrain analysis to quantify SOC dynamics and soil redistribution relationship and their responses to landscape topography in an Iowa cropland field with soybean/maize (C3/C4) rotation. The historic orthophotos and 137Cs were used to reflect soil redistribution before and after the 1960s, respectively. Topography‐based models were developed to simulate 137Cs inventory, SOC density, and C isotopes using stepwise principal component regression. Spatial patterns of SOC were similar to soil erosion/deposition patterns with high SOC density in depositional areas and low SOC density in eroded areas. Soil redistribution, SOC density, and isotopic signature of SOC (δ13C) were highly correlated with topographic metrics, suggesting that topographic heterogeneity drove the spatial variability in erosion and SOC dynamics. Considering the isotopic composition of SOC, C3‐derived SOC density was strongly controlled by topographic metrics, but C4‐derived SOC density showed weaker expression of spatial pattern and poor correlation to topographic parameters. The resulting topography‐based stepwise principal component regression models captured more than 60% of the variability in SOC density, δ13C, and C3‐derived SOC density but could not reliably predict C4‐derived SOC density. Our results indicate that exploring C isotopes in response to soil erosion is important to understand the fate of eroded SOC within croplands under C3/C4 cultivation.
6534. 题目: Changes in soil properties and soil organic carbon stocks along an elevation gradient at Mount Bambouto, Central Africa
作者: Désiré Tsozué, Jean Pierre Nghonda, Paul Tematio, Simon Djakba Basga
摘要: The study was designed to investigate the influence of elevation gradient on soil properties and soil organic carbon (SOC) in the Bambouto Mountain in Western Cameroon and the subsequent consequences of human activities on these SOC contents. Five sites, Bawa, Zavion, Totap, Camp Bororo and Meletan, were selected between 1400 m and 2740 m altitude to conduct the study. Three sampling points per site were allocated and each selected point was sampled using depth increments of 25 cm from the soil surface. The studied soils are characterized by low gravel contents. SOC contents and stock (SOCS) decrease with depth at all sites and increase along the elevation gradient, reaching the highest content (123.67 ± 30.44 g kg−1) at 2100 m a.s.l. Higher SOCS (157.14 ± 23.75 Mg ha−1) were found in 0–25 cm depth at Meletan at 2740 m a.s.l. while the lowest SOCS (86.04 ± 3.19 Mg ha−1) in the same depth was found in Bawa at 1500 m a.s.l. It increased and was significantly correlated with elevation (r = 0.86; p < 0.05), reaching a total of 302.15 ± 34.55 Mg ha−1 at 2740 m a.s.l. The difference might be attributed to longer vegetative growing periods at the high altitude without human interference in comparison with the lower altitude. Amorphous Fe and Al exhibited weak correlations with total SOCS along the altitudinal gradient, implying that their role on the stabilization of SOC might be little. The accumulation and stabilization of SOC is ascribed to clay content, parent material, climate and vegetation, which are controlled by the elevation gradient.
6535. 题目: Systematic chemotaxonomic profiling and novel paleotemperature indices based on alkenones and alkenoates: potential for disentangling mixed species input
期刊: Organic Geochemistry
作者: Yinsui Zheng, Patrick Heng, Maureen H. Conte, Richard S. Vachula, Yongsong Huang
摘要: The unsaturation indices (U37K, U37) of long chain alkenones are powerful paleotemperature proxies and have been widely applied for sea surface temperature (SST) reconstructions in the past three decades. However, these indices encounter major difficulties in systems harboring different alkenone-producing haptophyte species, such as saline lakes and marginal ocean environments. All haptophytes produce C37 alkenones, but different species often display large differences in temperature calibrations and may bloom in different seasons, hindering the use of U37K, U37 indices for reliable paleotemperature reconstructions in mixed systems. To overcome these problems, we have recently reported a new analytical method that allows comprehensive separation of up to 32 alkenones, alkenoates and their double bond positional isomers in culture and sediment samples. Here we report a systematic analysis of alkenones and alkenoates from six haptophyte cultures growing at a wide range of temperatures (4–25 °C). Together with a compilation of 230 previously published culture data sets, we present here systematic calibrations of temperature-sensitive indices based on all alkenone and alkenoate homologues (including isomers). Using this dataset, we extract systematic chemotaxonomic criteria for differentiating individual haptophyte species and demonstrate such chemotaxonomic features can be encoded into a machine learning model for reliable species identifications. Specifically, we show that temperature calibrations based on C38 methyl ketones and C39 ethyl ketones are potentially useful for disentangling mixed inputs in estuarine systems where Group III (E. huxleyi) and Group II alkenones mix, and that C36 ethyl alkenoate isomeric ratios display minimal species heterogeneity and are potentially more suited for reconstructing temperatures in mixed systems with different Group II haptophytes. Using the culture data as base profiles, we construct a mathematical model for estimating percentage inputs from alkenones of different Isochrysidales groups in mixed systems, with potential implications for inferring past salinity changes. Overall, the results from this study demonstrate important new applications of alkenone and alkenoate biomarkers in paleoclimate and paleoenvironmental research.
6536. 题目: Effective treatment of reverse osmosis concentrate from incineration leachate using direct contact membrane distillation coupled with a NaOH/PAM pre-treatment process
作者: Jinyu Shi, Yan Dang, Dan Qu, Dezhi Sun
摘要: Reverse osmosis is frequently used to process biologically treated leachate from municipal solid waste incineration plants. Reverse osmosis concentrate from incineration leachate (ROCIL) contains extremely high concentrations of monovalent and divalent ions (e.g. Na+, K+, Mg2+, and Ca2+) and some refractory organic pollutants (e.g. humic substances). In this study, lab-scale direct contact membrane distillation (DCMD) coupled with pre-treatment was applied to treat ROCIL. NaOH and polyacrylamide (PAM) chemical precipitation and coagulation pretreatment effectively removed Ca2+ and Mg2+ (>99%) from the ROCIL, which also significantly improved the treatment efficiency of DCMD and slowed down membrane fouling caused by Mg5(CO3)4(OH)2·4H2O and CaCO3 scaling on the membrane surface. During the long-term operation of DCMD, ROCIL was concentrated 21 times and nearly all of the inorganic ions (>99.9%) and organic matter (>99%) were removed from the pre-treated ROCIL. A strong interaction occurred due to the accumulation of humic substances and metal ions in the feed solution, which lead to inorganic and organic scaling deposited on the membrane surface and pores, but the wetting phenomenon was not serious. These results demonstrated that DCMD coupled with NaOH/PAM pre-treatment can be a potential alternative for further treatment and concentration of ROCIL to obtain high quality water.
6537. 题目: Potassium lignosulfonate as a washing agent for remediating lead and copper co-contaminated soils
期刊: Science of The Total Environment
作者: Qianjun Liu, Yu Deng, Jiepeng Tang, Di Chen, Xiang Li, Qintie Lin, Guangcai Yin, Min Zhang, Huawen Hu
摘要: Lignin is a renewable aromatic polymer which is present in large quantities in the cell walls of terrestrial plants and is the main binding agent for fibrous plant components. Potassium lignosulfonate (KLS), as a by-product of pulping processes, can be applied to agricultural fields as a soil conditioner and chelate fertilizer. In this study, based on its solubility and complexing ability, batch washing and column leaching was explored to evaluate the potential application of KLS in the washing remediation of soil contaminated with lead and copper. Under optimum conditions KLS concentration of 8%, pH of 5.24 and 6 h duration, the removal ratios for the simulated and mining area soils in the batch experiment were 67.40% and 52.87% respectively, for Pb and 73.42% and 55.20% respectively, for Cu. In the column leaching experiment, the removal efficiencies of Pb and Cu increased with solution volume and that the removal ratios of the simulated and mining area soils were 36.46% and 20.31%, respectively, for Pb and 39.74% and 22.76%, respectively, for Cu. KLS can reduce the ratio of acid-soluble and reducible fractions, which may have the most potential hazardous and poisonous for plants. Cation exchange capacity (CEC) and pH of soil were all stable after washing. However, the organic matter and available K, N, and P in the treated soil, which are important factors for plant growth increased significantly. This study showed that KLS can remove Pb and Cu from soil, while improve nutrient (ammonium nitrogen, available phosphorus and available potassium) levels of soil.
6538. 题目: Assessing paleohydrologic controls on the hydrogen isotope compositions of leaf wax n-alkanes in Chinese peat deposits
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Xianyu Huang, Philip A. Meyers
摘要: The high concentrations of lipid biomarkers in peat and the close relation between peatland development and hydrological conditions merit further assessment of the paleohydrological proxy potential of the 2H/1H ratio of leaf wax n-alkanes (δ2Halk) in peat deposits. In the context of the dynamics of the East Asian summer monsoon, detailed investigation of modern processes is an important way to improve our understanding of the controls on δ2Halk records from Chinese peat deposits. This review first synthesizes the results of investigations of modern processes in the Dajiuhu peatland of central China, complemented by results from other peatlands and nearby non-peatland sites, to evaluate how the 2H/1H ratio changes from source water to leaf water and then to lipids in leaf waxes and ultimately to peat deposits. The results reveal that the precipitation δ2H values and the peatland plant types are the two major factors that control the δ2Halk signals preserved in peat at Dajiuhu. Comparison of results from Holocene δ2Halk sequences from other Chinese peat deposits illustrates how peat δ2Halk values respond to paleoclimate changes on centennial to millennial timescales throughout the East Asian summer monsoon region. Finally, proposed incubations of peat-forming plants in controlled chambers that could assess the response of plant δ2Halk values to environmental stresses are described. As an example, responses of the compound-specific biomarker δ2H and δ13C values of Sphagnum, the dominant plant in the Dajiuhu peatland, could provide important information on the symbiotic relation between Sphagnum and microbes. It is expected that experiments such as these that combine the carbon and hydrogen isotope compositions of multiple lipids will yield important new insights into the responses of peatland ecosystems to climate changes.
6539. 题目: Effect of biochar on the physical and structural properties of a desert sandy soil
作者: Giorgio Baiamonte, Giuseppina Crescimanno, Francesco Parrino, Claudio De Pasquale
摘要: Biochar application to soil can be considered as a means to improve soil quality, thereby optimizing irrigation management and reducing irrigation needs, especially in dryland regions. This paper is aimed at investigating the effect of biochar (BC) on a desert sandy soil (Al Foah, United Arab Emirates) in terms of bulk density, porosity, water retention, plant available water (AWmax), aggregate stability (AS) and specific surface area (BET-SSA). BC was produced from forest biomass (Italy). Soil water retention was measured by the High Energy Moisture Characteristic (HEMC) and by pressure plate measurements, by using BC fractions equal to 0 (soil only), 0.014, 0.091, 0.23, 0.33 and 1 (BC only). The results indicated that BC significantly (p = 0.05) increased soil porosity and the amount of storage pores. As a consequence, water retention was enhanced and AWmax from 19.3 mm/m for the sandy soil (fbc = 0), to 60.8, 102.3 and 107.6 at fbc = 0.091, 0.23, and 0.33, respectively, was raised. No significant effects of BC were detected on the soil water retention curve of the BC-amended soil at fbc = 0.014, compared to the original condition. The significant increase in the structural index (SI) at fbc, ≥0.091, indicated that BC improved soil aggregate stability. The BET-SSA was measured by nitrogen adsorption measurements and indicated that the connected porosity was significantly increased by the 0.091 BC fraction. Both AWmax and SI were found to be correlated with BET-SSA. This showed an outcome that has been so far little investigated, namely that the BET-SSA played a significant role in the mechanism affecting the soil response to BC addition. The results showed that application of BC can improve soil structure and water retention and therefore optimize irrigation management by reducing irrigation needs, in the Al-Foah area and/or in similar dryland regions.
6540. 题目: Variability of the Pacific-derived Arctic water over the southeastern Wandel Sea shelf (Northeast Greenland) in 2015-2016
期刊: Journal of Geophysical Research: Oceans
作者: Igor A. Dmitrenko, Sergei A. Kirillov, Bert Rudels, David G. Babb, Paul G. Myers, Colin A. Stedmon, Jørgen Bendtsen, Jens K. Ehn, Leif Toudal Pedersen, Søren Rysgaard, David G. Barber
摘要: A portion of the freshwater transport through Fram Strait consists of low salinity Pacific‐derived Arctic water flowing southward along the east coast of Greenland. The pathways of this water are currently unclear. An Ice Tethered Profiler deployed over the southeastern Wandel Sea shelf (Northeast Greenland) in May 2015 collected a profile every 3 hours for a year recording salinity‐temperature‐depth (CTD) and Colored Dissolved Organic Matter (CDOM) fluorescence. This was accompanied by velocity observations. The CTD data revealed that the sub‐surface water (~15‐85 m depth) characterised by high CDOM resembles the “cold Halostad” in the Canada Basin formed by the injection of Pacific water. A coastal branch of the Pacific water outflow from the Arctic Ocean supplies the Wandel Sea halostad, which shows a clear seasonal pattern. From July to October‐November, the halostad is shallow, more saline, warmer, and with less CDOM. Conversely, from November to April, the halostad deepens, cools, freshens and CDOM increases, likely indicating a higher fraction of Pacific winter water. The CTD surveys, wind and current data, and numerical simulations show that the seasonal variation of wind over the continental slope likely controls seasonal changes of this intermediate water layer. Over northeast Greenland, winter winds have a northerly component from November to April, favouring Ekman transport of the Pacific‐derived water to the Wandel Sea shelf. In contrast, the prevailing southerly summer winds result in retreat of the Pacific‐derived water off the shelf. The landfast ice off‐slope extension modifies wind‐forcing disrupting seasonal patterns.